Gatling gun build

[JonesL]

Hello All.

Just joined the forum and thought I'd share a project or two. Been a machinist and foundry pattern maker for about 50+ years. I've had benefit of some old timers who were willing to share tricks they'd learned over the years. As a result I think after a few dozen years or so, I'm starting to get the hang of this metal working business.

Here are some pictures of my second Gatling. This one is a "Commercial Model of 1885". Six-barrel in .45-70 caliber and tripod mounted. I build in 12" to the foot scale-- easier to see the details. Before starting this project, I collected everything I could find in period photographs showing Gatling guns in order to get an idea of the little details and how this or that part was made.

Pouring cast iron tripod parts, manganese bronze rough casting set, breech casing w/ etched details, gun on the bench, tripod and turntable detail.

https://ibb.co/h25g08G
https://ibb.co/tKcVfXr
https://ibb.co/LvybD0Q
https://ibb.co/VMVnTHm
https://ibb.co/g3KZycB
https://ibb.co/tmL3W3r

[Roller]

Very impressive!  Having casting capability is an asset to building one of these guns.

Frank

[JonesL]

Thanks for the kind words, Frank.
Access to bigger machinery helps too. Here's the breech casing set up on a Bullard (Vertical Turret Lathe) to do the internal boring.

https://ibb.co/ss1zVKg
https://ibb.co/SBRmbWD

[Dave]

Thats cool stuff!

Arent you one of Paul Moores friends?

[JonesL]

Yep. I talked to Paul when I first started building in 2003. Met him and his son in person at one of the Denver gun shows a couple of years later. He let me lend a hand in making the foundry patterns for a miniature badge plate for his guns. Always a great guy and happy to share information and Gatling stories.
He'll be missed.

[Sparky_NY]

That is some beautiful work !     Casting really adds authenticity to a gatling.   

[JonesL]

Very true, Sparky.

But I must admit that sometimes I do cheat a little. I've machined parts out of billet then textured them with a needle scaler (used to chip mill scale and rust from steel). I also have taken a part out of the mill then put it back in by just eyeballing it. The misalignment can end up looking like parting lines from the mould halves.
Sometimes weathering can add to the illusion too. To get an original part look, just giving it a good rub down with a scotch brite pad does a good job of knocking off the sharp edges.

Here are a couple of pictures of a set of brake backing plates I made for my 1921 Harley board track racer.
Started with a couple of pieces of 6061T6 "tool plate", machined them and then threw in my electro-etching set-up, primarily to etch the lettering.
The "mask" I used is spray can primer and it's slightly porous which lets the electrolyte penetrate it to a small degree. Gloss if I don't want the solution leaching through.
The result; my hours old backing plates now look as "original" as the rest of the bike.

https://ibb.co/2s6gkbB
https://ibb.co/9GqZRYf

[Sparky_NY]

Those brake plates look fantastic, never suspect they were not original.     What do you use for electrolyte when etching?     Never seen etching done on aluminum, only brass/copper and that was non electrical.      Someday, I want to make about a 3-4" medallion for my .357 gatling, etching would be a possibility but I have zero experience.

[JonesL]

My electrolyte is plain ol' salt water for better conductivity. My set-up is a clean five-gallon bucket, a home car battery charger and knowing a couple of tricks;

I use Contact self-adhesive shelf paper and cut out my design with an Xacto knife.
For anyone with access to an outfit that makes embossing dies to do high end stationary or wine labels; You can get a magnesium made that has all kinds of depth. All you need is camera ready vector artwork and tell the etching shop you want your job to be done "right reading" (the die reads correctly and not backwards like a rubber stamp), and "black up" (means the lettering and border is raised above the background).

For electro-etching;
Fill bucket enough to completely submerge the part. Connect positive to the work piece and negative to a metailic plate of the same material you're etching. Etching aluminum = aluminum plate, steel = steel plate.
Insert common sense disclaimers here>> Wear rubber gloves!! Remember, we are playing with electricity here.<<
>> Do any etching jobs outdoors!! And I don't mean out in the garage with the door open. As the etching process is working, gases you shouldn't be breathing are being released.<<
>>If you want to check on your progress, turn off the battery charger, don't just unclip your leads. (Refer to Common Sense disclaimer 1.)<<

Here's Trick #1 The plate should cover the area to be etched and be positioned an equal distance from the work piece using an insulating spacer; nylon, wood blocks, anything that won't create a dead short. If you give yourself enough space between the two, you can even peek in and see how deep your etch is.
A small scrub brush or old toothbrush is handy to get the sludge that collects out of the etch.
If you were to use a bolt for your negative electrode instead of a plate that overshadows the area to be etched, the etch closest to the bolt will deeper 'cause electricity follows the path of least resistance. The farther away form the negative electrode, the shallower the etch.
I also mask off the back side of the plat I'm etching with gloss spray paint or self adhesive shelf paper because any bare metal will also be affected (etched).

Here are some pictures of my set-up for some motorcycle parts I did.

https://ibb.co/C2m0302
https://ibb.co/D9K4FDC
https://ibb.co/LxfGCcc

[Sparky_NY]

Thanks for all the great info !        I think I understand the basics,  probably will do some experimenting to really get a grasp of the process.

One question I have:    When etching, the area not etched is masked off but as the etching proceeds the side walls of the characters will not have any resist,   won't the etching cut into those side walls of the raised characters?     I am guessing that the depth of the etching is limited to quite shallow because of this.

I seen a etched brass medallion for a .22 gatling (small, about 1-1/2" dia) that a local fellow did.    He used a process of printing the design on a laser printer and transferring the toner from the paper to the metal as a etch resist.    The end product came out pretty nice.     On the surface it seems like a relatively easy process for a novice.

[JonesL]

You're right. Once the etching makes it past the mask, it will continue sideways in addition to down. Most of my electro-etching is lettering down into the background and there you can get a pretty deep etch.
For raised lettering, you have to watch the process closer and my guide is when I start to see the mask start to lift on the finer detail, I stop.
>>With any metal working or etching process; practice on some scrap first to get a feel for the job.<<

For extra fine detail I use this outfit http://www.img-electromark.com/ I send them my artwork and they convert it to a stencil, basically a very fine mesh silk screen. I tape the stencil down and when my electrical current is applied the electron flow is only through the open mesh. For this fine line etching, I set my battery charger on 2 amp trickle and have even used a Q-tip alligator clamped to the negative lead and the tip dipped into the electrolyte. Pictures are of that process and the results.
Last two are of chemical etching.

https://ibb.co/XjPJxcv
https://ibb.co/j5d7Yzv
https://ibb.co/gdnpnnH
https://ibb.co/3fMRfRm
https://ibb.co/nQbWV5g
https://ibb.co/LPX5jwm

Another process, this time chemical etching on brass, is to use ferric chloride (used to make printed circuit boards). Read up on ferric chloride before you start as it has some odd properties; "Ferric chloride is not an acid but acts like one in the presence of water" which means that the diluted solution is more active than the concentrate.
Be very careful of spills because even if you wipe it up immediately, it'll leave a mark on any brass it touches. Get a drop or two on your skin and you'll end up with a yellowish stain that's as permanent as a USDA beef tattoo.

A silk screen shop screen prints my artwork on brass sheet (make sure any lacquer or wax coating is completely removed down to bare brass first) and the ferric chloride goes after the copper in the brass alloy. This is a very slow process but gives super fine detail. Coat the back of the sheet with a mask of your choice or the plate will be thinner than when you started.
Again, when I start to see the mask lifting, I stop and rinse off the surface with a baking soda and water mix and a scrub brush to neutralize the solution. Dip in acetone to remove the screen print and you're done. Ferric chloride can be used over and over so i just pour off the solution into a container for the next job. Hazmat rules apply with ferric chloride.
With the electro-etching process, you're only dealing with salt water electrolyte and that can be poured down the drain or on weeds you want to get rid of.

[Roller]

Very interesting, thanks for joining the forum.  I am learning a lot from your posts.  Thank you!


Frank

[Sparky_NY]

That Bruce feed magazine is another item of extreme interest.    A few of us here on the forum were looking to make one,  some of us got a start on it.   Nobody found any really good drawings and detail of it so a lot of assumptions were made.

Does your magazine switch automatically to the next column of bullets when one goes empty?

As for the gatling medallion, another option was to engrave it with tiny endmills on the cnc mill.    In fact, I bought a 24,000 rpm spindle to use as a sub spindle with that in mind.    Like many things, I have gotten side tracked on other projects but still will do a medallion at some point before too long.

[JonesL]

Thanks for the welcome Frank.
I've only got one or two tricks I'd like to keep to myself but most everything else is stuff that was shared with me by old timers. I'm just passing along their kindness and generosity. Over the years I've picked up techniques on everything from patinas and weathering to set-ups and machining. As a result I seem to manage to figure out 5 or 6 ways of setting up or holding parts instead of the obvious 1 or 2. Opens up a whole bunch of associated tasks most people think are impossible for the average machinist.
I'm constantly amazed at the number of parts I'm told I can't make. I just wish the naysayers would have let me know before I made, installed and have the part working.

Another love is old Harleys. Here's a 1921 board tracker that I putt around on when the weather's nice. Bought the original bike in 1998. I got it out of storage and began what's been a 6 year restoration / build. All the original parts I took off have been preserved and put away.
I replaced the original pocket valve motor with one from a 1971 Harley Sportster but I did it by modifying the engine to fit the frame, not hacking up the frame to take the motor. Done that way, I can have the bike back to completley original condition in about a day.
Modern brakes let me get stopped. All new cotton-wrapped wiring keeps the vintage look along with details like using friction tape instead of plastic electrical tape.
Where I've needed extra room, like getting the drum brakes in the front end and working right, I duplicated the original fork castings, just with wider dimensions.
Knowing a trick or two about metal finishing and patinas let me keep an original "barn find" look that I find more interesting than the museum-grade restorations that some older bikes have gone through. Between its 100 year old frame and my 76 year old frame, we don't go very far or very fast but it definitely gets thumbs-ups and smiles whenever I take it out.

https://ibb.co/Yb2L3FS
https://ibb.co/PDwdNrz
https://ibb.co/NZPdJRd

[JonesL]

No Sparky, my Bruce feed cartridge pendulum has to be nudged over. If the detent spring is too soft it may not hold to one side or the other and cause feeding problems. We are after all, just holding the rounds in the "T"-slots by their rims and counting on gravity and small amount of shaking to keeping them dropping.
I think I read somewhere that some Gatlings shipped with Bruce feed mechanisms were eventually sent back to Colt and refitted with hoppers for the "straight feed case" (stick magazine).

All Gatling's gravity feed systems; Broadwell Drum, straight feed cases and L.F. Bruce gravity feeds were notorious for not working once they exceeded a point in muzzle depression or elevation. Accles solved that problem with a fully mechanical feed design but they're like a giant clockwork inside and sensitive to dents and dings anywhere in the outer surfaces "causing derangement of the feeding mechanism" as they say in one of my Ordnance Memoranda.
That and the large brass drum sitting on top made for a very inviting target for opposing marksmen.

[Sparky_NY]

Very interesting, thanks for joining the forum.  I am learning a lot from your posts.  Thank you!


Frank

Yes, thanks much for joining !      All the info has been extremely interesting.

[bruski]

Nice work Jones. I have been away for a while and have some ketching up to do. The wife talked me into having a smaller new house built before the lumber prices went through the roof. It's finished now but the temperature outside is 117 degrees and to hot to do any moving.
bruski

[Sparky_NY]

Welcome back Bruski !    Missed having you around.

[bruski]

HI Sparky,
  Nice to hear from you again. I haven't done to much in the machine shop lately, but hopefully sooner than later.

bruski